The present invention relates to slot machines of the type which selects combinations of symbols at random during each game and awards prizes when predetermined prize-winning combinations occur on designated prize-winning rows.
As is well known in this art, slot machines of this type have a plurality of rotatable reels each of which is provided with an annular row of various symbols on the outer surface thereof. During a game, each reel is caused to rotate, and is stopped at random at one of possible stop positions in each of which it displays a corresponding symbol to a player through a window. Recently, there have been proposed slot machines of this type, which use a simulated video display of a plurality of rotating reels. In either case, such slot machines are provided with a starting lever or button for starting the reels to rotate all at once, stop buttons for selectively individually stopping the respective reels preferably at mutually different moments of time after the start of the reels, and detector means for detecting the occurrence of the prize-winning combinations on the designated prize-winning rows.
In general, slot machines are prepared for playing a game only by inserting a coin or coins into a slot thereof after a previous game has ended. Because, in such slot machines, it is usual to play the same game repeatedly, it is a nuisance for the player to have to insert coins into the slot for every game. In order to avoid this, there have been developed slot machines of the type which allows inserting a number of coins at one time before playing games and which counts down the number of coins used every game. Such slot machines are convenient to operate, because a game can be repeated many times without inserting coins before every game.
In order to increase the player's interest in the game, there have been provided slot machines of the type which allows players to select prize-winning rows. Slot machines of this type have, for example, three reels each of which, during a game, is stopped at random at one of the possible stop positions in each of which it displays a corresponding set of three symbols arranged in a vertical row in a window. Therefore, the slot machine selects three combinations of symbols arranged in three horizontal or transverse or even diagonal rows in the window and awards prize coins when predetermined prize-winning combinations occur on any of the selected rows as a prize-winning row. In slot machines of this type, the number of prize-winning rows is selected corresponding to the number of coins inserted into the slot machine. For example, the slot machine assigns the center row as the prize-winning row for one coin, the upper two rows for two coins and all three horizontal rows for three coins. After the completion of the step of assigning prize-winning rows, the operation of the starting lever or button is made possible, permitting the player thereafter to start the reels.
However, a slot machine of the type which allows inserting a number of coins at once as well as selectively assigning prize-winning rows, does not permit assigning prize-winning rows corresponding to the number of coins inserted immediately before each game. Such slot machines, therefore, require the provision of means which is operated selectively to assign prize-winning rows before the operation of starting lever or button for starting the rotation of reels.
The provision of assigning means, which obliges a player to operate a starting lever or button for starting the rotation of the reels every time the assignment of prize-winning rows is made, encumbers the game, because the starting lever or button has to be operated a number of times corresponding to the number of games repeatedly tried.